Well screen cleaning device

ABSTRACT

A well-screen cleaning device for unblocking clogged wells by blowing accumulated foreign material from the mesh of the well screen with rapidly expanding gasses without damaging the screen to provide screening for water after the cleaning operation and to obviate replacing the screen, comprising a case having an axial channel opening downwardly from the case and an explosive charge in the channel for producing the expanding gasses upon its detonation. Electric wires leading to the charge comprise both the lowering means for the device in a well casing and the means for detonating the charge. A top vent aperture in the case emits a small volume of gas upwardly creating a resilient blocking turbulence in the casing above the main volume of expanding gasses to hold down the major volume of the expanding gasses for projection against the screen without damaging the screen.

United States Patent 91 Hastings 1March 20, 1973 Primary Examiner-Verlin R. Pendegrass Attorney-William T. Sevald [5 7] ABSTRACT A well-screen cleaning device for unblocking clogged wells by blowing accumulated foreign material from the mesh of the well screen with rapidly expanding gasses without damaging the screen to provide screening for water after the cleaning operation and to obviate replacing the screen, comprising a case having an axial channel opening downwardly from the case and an explosive charge in the channel for producing the expanding gasses upon its detonation. Electric wires leading to the charge comprise both the lowering means for the device in a well casing and the means for detonating the charge. A top vent aperture in the case emits a small volume of gas upwardly creating a resilient blocking turbulence in the casing above the main volume of expanding gasses to hold down the major volume of the expanding gasses for projection against the screen without damaging the screen.

2 Claims, 4 Drawing Figures a W F NVE JAMA'J z. z. HA6

PATENTED MAR 20 I975 i Ha n 1. z

ATTORNEY WELL SCREEN CLEANING DEVICE This invention relates to well screen cleaning devices and in particular to a device producing expanding gasses against and through the screen mesh to remove foreign material therefrom without damaging the screen.

The present day commercial practice of cleaning the screens of water wells, when clogged with calcium carbonate, iron, and other materials including small stones and sand particles, is to introduce acid into the well. This is in spite of the fact that oil wells and other large wells are perforated and activated with explosive charge devices. This practice is used because the ordinary water well driller is not familiar with explosive charge devices and also because he is not trained to use them. The acid practice only removes the foreign material but also destroys the screen and renders the water unpotable for months.

With the foregoing in view, it is a primary object of the invention to provide an explosive charge, expanding gas, well screen cleaning device which is simple in design and construction, inexpensive to make and use, which the ordinary water well driller may use with safety, and which is dependable and efficent in operation.

An object of the invention is to provide a well cleaning device having a relatively safe and uniform explosive charge to obviate damage to the well and injury to the user.

An object of the invention is to provide an electri cally detonatable charge which is easily exploded by connection to a source of electric power.

These and other objects of the invention will become apparent by reference to the following description of a well cleaning device embodying the invention taken in connection with the accompanying drawing, in which:

FIG. 1 is a vertical cross-sectional view of a well casing in the ground with the device shown in elevation suspended therein adjacent the perforate well screen and supported by the electric wires for detonating the explosive charge.

FIG. 2 is a greatly enlarged vertical cross-sectional view of the cleaning device shown in FIG. 1, showing the attaching bail in elevation.

FIG. 3 is a top plan view of the device seen in FIG. 2, and

FIG. 4 is a bottom plan view of the device seen in FIG. 2.

Referring now to the drawing wherein like numerals refer to like and corresponding parts throughout the several views, the well screen cleaning device 9 shown therein to illustrate the invention comprises an elongated case 10 having a top end 11, a bottom end 12, and an axial chamber 13 leading from a point spaced below the top end 11 through the bottom end 12. A ball 14 is welded to the case 10 at the top end 11 and constitutes attaching means for the lowering means. A relatively small orifice 15 leads through the top end 11 of the case 10 and communicates with the channel 13.

A dynamite cap 16 or other explosive charge having an insulating layer 17 is positioned in the channel 13. Wires 18 and 19 are connected to the cap 16. The wires 18 and 19 may lead around the case 10 and up the channel 13 through the bottom end 12. However in the preferred embodiment, the wires 18 and 19 lead through the aperture 15 at the top end of the case 10 and down through the channel 13 to the cap 16. The wires 18 and 19 are tied to the bail l4 and constitute the lowering means. The device 9 is now ready for use in cleaning a well screen.

The well casing 20 extends into the ground 21 and has a perforate or mesh portion adjacent its bottom end which constitutes the well screen 22.

In use and operation, the operator lowers the device 9 down the well casing 20 by playing out the wires 18 and 19 until the device contacts the bottom end of the well casing 20. The operator then raises the device 9 until it is adjacent or slightly above the screen 22 as shown in FIG. 1. The operator then connects the wires 18 and 19 to a source of electric power and this detonates the cap 16. Upon explosion of the cap 16, rapidly expanding gasses are produced in and expelled from the channel 13 toward the screen 22 and impinge on the screen 22 under about PSI. The gasses quickly force their way through the screen 22, and in their travel, displace the foreign material in the perforations or mesh and thus unclog and open the screen. Upon the explosion of the cap 16, the gasses also expand upwardly in the channel 13 and a quantity of gas under pressure is emitted through the orifice 15 into the well casing 20 above the device 9 and also above the main gas discharge at the bottom end 12 of the device 9. The gas discharge from the orifice 15 creates a turbulence in the fluid in the casing 20 above the device 9 and above the main gas discharge. This turbulence creates a resilient blockade above the device 9 and above the main gas discharge deterring upward surge of the gas and also resiliently deterring upward travel of the device 9. The main gas discharge is thus resiliently blocked at the screen 22 and resiliently directed againist the screen 22.

The case 10 is preferably made of stainless steel as is the ball 14. The bail may be securely arc welded to the case 10 by drilling the bail receiving apertures close to the side wall of the case and then arc welding through the case 10 to the bail 14.

The invention is defined in the appended claims. I claim: 1. A well-screen cleaning device for unblocking clogged water wells by blowing accumulated foreign matter from the mesh of the screen with rapidly expanding gasses to open the screen mesh for the passage of water without damaging the screen mesh to provide screening of foreign material from the water after the cleaning operation and to eliminate replacing the screen, comprising,

an elongated case having a top end, a bottom end, and an axial channel leading through said bottom end; said case having imperforate solid side walls to prevent direct impingement of expanding gases against a screen; said case having a relatively thick side wall surrounding said axial channel and a relatively thick top wall over said axial channel for resisting gas pressures generated within said channel and to direct expanding gasses downwardly-outwardly of said axial channel past said case bottom end axially into a well casing and parallel relative to a screen; and,

attaching means on said case for securing lowering means to said case for lowering said case down a well casing to a point adjacent the screen portion of the well casing;

an electrically actuatable explosive charge being positionable in said case axial channel, and wires leading from the explosive charge being connectable to a source of electric power;

said device when equipped with a charge, wires, and

2. In a device as set forth in claim 1 said top wall having an aperture leading upwardly from said axial channel;

said aperture being relatively smaller in cross-section than said axial channel to allow only a relatively small volume of expanding gasses in said channel to emit into the well casing above said device compared to the large volume'of expanding gasses emitting from said axial channel at said bottom end;

said gas emission from said aperture in said top end creating a resilient blocking turbulence in the well casing above the major volume of said gasses emitting from said axial channel at said bottom end creating an impediment to gas escape upwardly in the well casing thereby directing the major volume of gasses generated toward the well screen without damaging the screen. 

1. A well-screen cleaning device for unblocking clogged water wells by blowing accumulated foreign matter from the mesh of the screen with rapidly expanding gasses to open the screen mesh for the passage of water without damaging the screen mesh to provide screening of foreign material from the water after the cleaning operation and to eliminate replacing the screen, comprising, an elongated case having a top end, a bottom end, and an axial channel leading through said bottom end; said case having imperforate solid side walls to prevent direct impingement of expanding gases against a screen; said case having a relatively thick side wall surrounding said axial channel and a relatively thick top wall over said axial channel for resisting gas pressures generated within said channel and to direct expanding gasses downwardly-outwardly of said axial channel past said case bottom end axially into a well casing and parallel relative to a screen; and, attaching means on said case for securing lowering means to said case for lowering said case down a well casing to a point adjacent the screen portion of the well casing; an electrically actuatable explosive charge being positionable in said case axial channel, and wires leading from the explosive charge being connectable to a source of electric power; said device when equipped with a charge, wires, and electric power being detonatable upon connection of the wires to the electric power whereupon the expanding gasses resulting from the explosion are rapidly axially introduced to the well casing and parallel at the screen and pressurize the area so that they drive through the screen mesh with spread-out equal force driving accumulated foreign material in the mesh outwardly of the mesh without localized impingement thereby opening the mesh of the screen for the movement of water therethrough into the well casing without rupturing the screen.
 2. In a device as set forth in claim 1, said top wall having an aperture leading upwardly from said axial channel; said aperture being relatively smaller in cross-section than said axial channel to allow only a relatively small volume of expanding gasses in said channel to emit into the well casing above said device compared to the large volume of expanding gasses emitting from said axial channel at said bottom end; said gas emission from said aperture in said top end creating a resilient blocking turbulence in the well casing above the major volume of said gasses emitting from said axial channel at said bottom end creating an impediment to gas escape upwardly in the well casing thereby directing the major volume of gasses generated toward the well screen without damaging the screen. 